1. Field
The disclosed concept pertains generally to electrical switching apparatus and, more particularly, to direct current electrical switching apparatus, such as, for example and without limitation, direct current circuit breakers. The disclosed concept further pertains to direct current arc chutes.
2. Background Information
Electrical switching apparatus employing separable contacts exposed to air can be structured to open a power circuit carrying appreciable current. These electrical switching apparatus, such as, for instance, circuit breakers, typically experience arcing as the contacts separate and commonly incorporate arc chutes to help extinguish the arc. Such arc chutes typically comprise a plurality of electrically conductive plates held in spaced relation around the separable contacts by an electrically insulative housing. The arc transfers to the arc plates where it is stretched and cooled until extinguished.
Typically, molded case circuit breakers (MCCBs) are not specifically designed for use in direct current (DC) applications. When known alternating current (AC) MCCBs are sought to be applied in DC applications, multiple poles are electrically connected in series to achieve the required interruption or switching performance based upon the desired system DC voltage and system DC current.
One of the challenges in DC interruption is to drive the arc into the arc chute, specifically at relatively low current levels. Some known DC switching products use permanent magnets to drive the arc into the arc splitter plates. However, they either provide only uni-directional current interruption, or they are relatively large due to the use of two arc chutes in order to achieve bi-directional performance.
There is room for improvement in direct current electrical switching apparatus.
There is also room for improvement in direct current arc chutes.